(1) Field of the Invention
This invention relates to a magnetic tape cassette for use in a magnetic record/reproduce apparatus such as a magnetic tape recorder, and in particular to a coding array for the cassette, such coding array comprising a series of coding holes which are sensed by the apparatus in which the cassette is loaded.
(2) Description of the Prior Art
In the evolution of the magnetic tape cassette/recorder interface, the choices in the early days were far simpler than they are today. For example, early magnetic tape recorders used only one size cassette, and, in that cassette, the tape thickness did not vary and the tape type did not vary. Accordingly, there was no need to provide a scheme allowing for the variation of these parameters. The only parameter of consideration in the early cassettes was associated with a record inhibit device generally provided on an edge of the cassette as a lockout tab which was removed to prevent accidental recording on the cassette.
Coding holes first were used in an 8 millimeter cassette developed for the video tape industry. Because tape type and tape thickness could be changed for the 8 millimeter cassette, it was decided to designate two coding holes provided on one side of the cassette for sensing tape type and tape thickness. The coding holes were provided at the edges of the cassette. Such a coding scheme was clearly devised without consideration for variations in cassette size, since, if the cassette were down-sized, the coding holes would have to be moved. And, if the cassette were enlarged, the larger tape reels of the larger cassette would again force the coding holes to be moved.